1. Field of the Invention
The present invention relates to an air bag system for vehicles, and more particularly to a passenger air bag system for vehicles, wherein the installation structure of an inflator is improved so that the assembly efficiency of the air bag system is increased, and the size of the air bag system is reduced so that compact design of the air bag system is possible.
2. Description of the Related Art
Generally, an air bag system for vehicles is mounted in front of a driver seat or a passenger seat in such a manner that a cushion of the air bag system is instantly expanded when a collision of the vehicle occurs for protecting a driver or a passenger from injury.
The air bag systems may be classified into a driver air bag system and a passenger air bag system. The driver air bag system is mounted to the steering wheel of the vehicle for protecting the driver from injury. The passenger air bag system is mounted to an instrument panel of the vehicle disposed in front of the passenger seat for protecting the passenger from injury. Basically, the driver air bag system is requisite, and the passenger air bag system is optional; however, vehicles with passenger air bag systems basically mounted therein for protecting passengers from injury are on the increase in recent years.
FIG. 1 is an exploded perspective view showing a conventional passenger air bag system, and FIG. 2 is a longitudinal sectional view showing the conventional passenger air bag system.
As shown in FIGS. 1 and 2, the conventional passenger air bag system for vehicles comprises: an air bag housing 4 mounted to an instrument panel 2; an inflator 6 mounted in the air bag housing 4 for discharging gas when a collision of the vehicle occurs; a cushion 8 accommodated in the air bag housing 4 such that the cushion 8 is expanded to the front of a passenger seat by means of gas discharged from the inflator 6; and a retainer 10 attached to the air bag housing 4 for supporting the cushion 8, the retainer 10 having a plurality of gas-guiding holes 10a for guiding gas discharged from the inflator 6 to the cushion 8.
The air bag housing 4 comprises: a cushion housing 12 formed in the shape of a box with the front part opened so that the cushion 8 is accommodated in the cushion housing 12 while being folded; and a can housing 14 connected to the rear part of the cushion housing 12, in which the inflator 6 is disposed.
The cushion housing 12 is provided along both longitudinal sides at the front part thereof with flanges 12a, respectively, which are fixed to the rear part of the instrument panel 2 by means of bolts. At the instrument panel 2 is formed a cut line 2a so that the instrument panel 2 is easily and smoothly broken along the cut line 2a by means of the expanding pressure of the cushion 8.
The can housing 14 is connected to the rear part of the cushion housing 12 in such a manner that the can housing 14 communicates with the cushion housing 12. The can housing 14 is fixed to a cowl cross member (not shown) disposed in the instrument panel 2 by means of a mounting bracket (not shown).
The inflator 6 is formed in the shape of a cylinder. The inflator 6 is provided on the outer circumference at one side thereof with a plurality of gas-discharging holes 16 for discharging gas when a collision of the vehicle occurs.
At one end of the inflator 6 is formed a fixing protrusion 18 having a male screw thread part formed on the outer circumference thereof, on which a fixing nut 20 is rotatably fitted so that the inflator 6 is attached to the side of the can housing 14. At the other end of the inflator 6 is formed a connector-connecting member 22 in such a manner that the connector-connecting member 22 is protruded outwardly. To the inflator 6 is fixed a connector 24, by which the inflator 6 is linked to an external device, through the connector-connecting member 22.
The inflator 6 is horizontally disposed in the can housing 14. At one end of the inflator 6 is formed a fixing protrusion 18, which is inserted through a through-hole 26 formed at one end of the can housing 14. The other end of the inflator 6 is inserted through an opening 28 formed at the other end of the can housing 14.
The retainer 10 is attached to the can housing 14 together with the cushion 8 by means of bolts such that the plurality of gas-guiding holes 10a formed at the center of the retainer 10 communicate with an inlet part of the cushion 8. The retainer 10 serves to support the cushion 8 so that the cushion 8 is not separated from the can housing 14 due to the pressure of the gas when the cushion 8 is expanded.
The operation of the conventional passenger air bag system with the above-stated construction will now be described. When a collision of the vehicle occurs, an operation signal is transmitted from an electronic control unit to the inflator 6 via the connecter 24, and then the inflator 6 is exploded by means of electric current from a power supply terminal for discharging gas through the gas-discharging holes 16.
The gas discharged from the inflator 6 flows along the can housing 14 so that the gas is supplied into the cushion 8 through the gas-guiding holes 10a of the retainer 10. The cushion 8 is expanded to the front of the cushion housing 12 by means of the gas supplied into the cushion 8.
The instrument panel 2 is broken along the cut line 2a formed at the instrument panel 2 by means of the cushion 8 expanded as described above. Subsequently, the cushion 8 is further expanded toward a passenger seated in the passenger seat, whereby shock transmitted to the passenger is effectively absorbed, and thus injury to the passenger is minimized.
In the conventional passenger air bag system for vehicles, however, the fixing protrusion 18 of the inflator 6 is securely fixed to a fixing part 30, which is formed by one end of the can housing 14, by means of the fixing nut 20. In other words, an additional fixing operation carried out by means of the fixing nut 20 is required when the inflator 6 is assembled. Consequently, the assembly efficiency of the inflator is deteriorated. Furthermore, it is difficult and troublesome to continuously or periodically maintain the fixing protrusion 18 and the fixing nut 20.
Torque control of the fixing protrusion 18 and the fixing nut 20 is required so that the fixing nut 20 is securely fitted on the fixing protrusion 18 while there is provided an appropriate fixing force between the fixing protrusion 18 and the fixing nut 20 on the basis of the explosive power of the inflator 6 and the structure of the air bag housing 4. Also, record control of the fixing protrusion 18 and the fixing nut 20 is required, which is performed by marking a fixing force between the fixing protrusion 18 and the fixing nut 20 at one side thereof for further reference.